On November 23, 2002, about 1630 eastern standard time, a Cessna 172K, N7192G, was substantially damaged during a forced landing after experiencing a total loss of engine power near Prestonsburg, Kentucky. The certificated flight instructor and student pilot were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local instructional flight conducted under 14 CFR Part 91. According to the pilot, the flight had departed the Paintsville-Prestonsburg-Combs Airport, Paintsville, Kentucky, about 1600. While in cruise flight, at 3,000 feet, the engine began to run rough. The pilot cycled the magneto switch and noted no changes in the engine performance. He then observed the oil pressure gauge in the "zero" position. The engine then lost total power, and a forced landing was performed to a field. A Federal Aviation Administration inspector examined the airplane after the accident, and observed substantial damage to the engine firewall, and the fuselage. The inspector also noted a 2-inch hole in top of the engine crankcase. Further examination of the engine revealed that the connecting rod and camshaft area of the number 4 cylinder had sustained extreme heating. The bottom half of the connecting rod was bent out of shape, with one of the rod end bolts remaining wedged in the rod end. The other rod end bolt was missing. The oil screen was removed, and small amounts of metal were observed trapped in the screen. Metal parts were also observed in the oil pan. There was no evidence of oil leakage. The engine had accumulated about 2,400 hours of operation since it's last overhaul conducted in 1986. An annual inspection of the airframe and engine was performed on August 23, 2002. A 50-hour inspection, which included servicing the engine with 7 quarts of oil, was conducted on November 21, 2002.